Southern California -- this just in

Freeway explosion caused concrete to boil over, blow out in chunks

December 15, 2011 | 4:55
am

A tanker truck explosion that closed the 60 Freeway Thursday was fueled by 8,800 gallons of gasoline and caused moisture inside the concrete overpass to boil over and blow out chunks of rubble, fire officials said.

"The explosion most witnesses heard was the concrete exploding from the extreme heat," said Montebello Fire Chief Tim Wessel.

Firefighters reported seeing pieces of metal and concrete dropping from the overpass as they arrived on the scene, officials said. Massive billows of black smoke rose from underneath the bridge as fire crews tried to beat back flames. They battled the blaze for about two hours before it was extinguished. Late Wednesday, crews were offloading the remaining fuel on the truck.

The cause of the fire had not been determined and was under investigation by the CHP.

Witnesses described hearing two explosions shortly after noon, the second of which caused floors to vibrate in nearby buildings.

Officials said it was unclear whether the truck had hit another vehicle, run over debris or had a mechanical problem. CHP investigators were planning to inspect the tanker to determine if brake or other mechanical failure was involved.

"It gave me a good scare," said Miguel Osorio, 25, who was helping customers inside a Chevron gas station when he heard the blasts.

He called a gas station closer to the freeway, fearing that it had exploded into flames. "The fire looked like it was coming from that general area," Osorio said.